<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>测试分支</title>
    <!--不允许缩放-->
    <meta name="viewport" content="initial-scale=1, maximum-scale=1, user-scalable=no">
    <!--chrome=1优先选择急速模式，优先选择chrome内核-->
    <meta http-equiv="X-UA-Compatible" content="IE=Edge,chrome=1">
    <!--<link rel="stylesheet " type="text/css " href="css/globle.css " />-->
    <!--<link rel="stylesheet " type="text/css " href="css/style.css " />-->
    <script src='js/jquery.js'></script>
    <!--<link rel="stylesheet" href="style.css">-->

</head>
<style>
    html{
        height: 100%;
    }
    body{
        width: 500px;
        margin: 0 auto;
        height: 5000px;
        background-position:center center;
        background-image:url(quan.jpg);
        background-repeat:no-repeat;


    }
    .to-top{
        background-color: red;
        position: fixed;
        width: 40px;
        height: 40px;
        border-radius: 50%;
        right: 20px;
        bottom: 20px;
    }
    .to-top::after{
        width: 0;
        height: 0;
        position: absolute;
        content:"";
        left: 8px;
        top:12px;
        border-bottom:12px solid #fff;
        border-right:12px solid transparent;
        border-left:12px solid transparent;

    }
</style>
<body>
<div class="to-top"></div>
</body>

</html>
<script>
    $('.to-top').click(function(){
        $('body,html').animate({
            "scrollTop" : 0
        },400)
    })
</script>
